1. Field of the Invention
The invention is directed to a hydrodynamic torque converter with a converter circuit having an impeller wheel, a turbine wheel and a stator wheel, with each of the impeller wheel and the turbine wheel having an inner wall connecting the individual blades of the wheels and which forms an inner torus with the other inner wall and each inner wall having an extension extending toward the other wheel.
2. Description of the Related Art
A torque converter having inner walls with extensions is known, for example, from FIG. 4 of reference DE 41 21 586 A1. This prior art device has a converter circuit with an impeller wheel, a turbine wheel and a stator wheel, wherein the individual blades at the impeller wheel and at the turbine wheel are connected with one another in an identical manner at their free ends by an inner wall. The inner walls which together form an inner torus have, at their radial outer side and radial inner side, an extension located opposite to the blades, wherein the extension extends essentially axially toward the other respective wheel. The axial distance between the two extensions is smaller on the radial outer side of these walls than on the radial inner sides. The extensions on the radially inner side are arranged to be close in the radial direction to a cover ring connecting the free ends of the blades of the stator wheel with one another.
Because of the inflation or swelling of the converter during operation caused by centrifugal force, the axial distance between the extensions of the two walls must be large enough to prevent an unwanted grinding contact. However, experience shows that a disadvantage of a large axial distance of this kind includes a decrease in hydrodynamic characteristic value, since there is an interruption in the flow guidance which leads to separation and therefore to whirling in the flow. A poorer efficiency and a lower transmission ratio result. This problem may be reduced in the radial inner region by the cover ring, but this increases the quantity of structural component parts, the manufacturing effort and the weight of the torque converter; moreover, the flow cross section for the converter fluid is reduced.